crypto: sha512 - Remove sha512_base.h
sha512_base.h is no longer used, so remove it.
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20250630160320.2888-17-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>